System for and method of hairpinning a remote PBX or KTS or gateway phone call to a local call

ABSTRACT

In a system having a switching device in a first location, and an extending device in a second location, a method of providing a communications link between (i) a first phone associated with the extending device and (ii) a second phone local to the second location and not associated with the extending device includes analyzing parameters associated with the first phone and the second phone so as to determine that the first phone and the second phone are local to the second location. The method further includes separating signaling data associated with the communications link from voice traffic associated with the communications link. The method further includes directing the signaling data through the switching device via an extension link between the switching device and the extending device, and directing the voice traffic between the first phone and the second phone.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] Not Applicable

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

[0002] Not Applicable

REFERENCE TO MICROFICHE APPENDIX

[0003] Not Applicable

BACKGROUND OF THE INVENTION

[0004] The present invention relates to telephone switching systems, andmore particularly, to conserving channel bandwidth in a communicationslink between a primary office and a remote location.

[0005] The majority of in-house telephone systems (e.g., PBX) in usetoday employ physical telephone units (referred to herein as “desksets”)that are wired into a switching device. The switching device, inconjunction with various processing components, provides a wide range offacilities and features to the deskset user. Such facilities andfeatures include voicemail, call transfer, and conferencing, amongothers. The deskset is a user interface device that is typicallycomprised of a microphone/speaker, standardized telephone keypad,feature keys, text display, and other visual displays (e.g., lamps orLEDs), and is used primarily to receive and place telephone calls. Thedeskset employs a fixed and proprietary protocol for communicating withthe switching device. Such protocols are typically restricted by thecharacteristics of the wire (i.e., the transmission path) that connectsthe deskset to the switching device.

[0006] Because the cost to acquire and maintain the switching device canbe significant, many organizations choose to install a central switchingdevice in a primary office, and allow users resident in remote officesto access the central switching device via extender links over thePublic Switched Telephone Network (PSTN). This arrangement, however, canlead to unfortunate situations that consume unnecessary channelbandwidth in the extender link between the central and remote locations.For example, FIG. 1 shows a central office in city X with a PBX switch10, and a remote office in city Y. The remote office in city Y utilizesthe PBX 10 at the central office in city X through an extender 12 thatcommunicates with a gateway 14 at the central office via an extenderlink 16 that exists, at least partially, within the PSTN. Suppose anoutside phone 18 calls the direct inward dialing (DID) number associatedwith a user phone 20 in the remote office. The extender 12 will detectthe incoming call and route the call to the PBX 10 via the gateway 14and the extender link 16. The PBX 10 detects the incoming call anddetermines that it is for the user phone 20 at the remote office. ThePBX 10 routes the call to the user phone 20 via the gateway 14, theextender link 16 and the extender 12. Note that channel bandwidth neededto be reserved on the extender link twice; once when the extender 12routes the call to the PBX 10, and once when the PBX 10 routes the callback to the user phone 20. The bandwidth reserved on the extender link16 is necessary only because the PBX 10 is located in a city differentfrom the source and destination of the call.

[0007] The same path, only in reverse, occurs when the user 20 phonecalls the outside phone 18. Further, since a call (in either direction)must traverse so many paths from city to city, the likelihood that atleast one of the paths will be disrupted, thus disrupting the call) isgreater than if the call remained completely in city Y.

SUMMARY OF THE INVENTION

[0008] As used herein, the term “hair-pinning” is the routing mechanismof voice calls at a remote office to a) save bandwidth, b) provide theleast-cost voice routing for two calling parties involving an extendedPBX user and a non-PBX user, or two extended PBX users c) and providesurvivability. The system also provides Toll Bypass functionality tousers directly connected to the PBX via a trunk extension.

[0009] The invention achieves the three objects above by intelligentlyturning on or turning off hair-pinned voice paths at a remote location,while still providing access to extended PBX features. The callsignaling data is still exchanged between the remote office and the mainoffice (with PBX) for a local call, but the least-cost voice path isdynamically chosen depending on a feature an extended PBX user selects.If the extended user chooses making or receiving a local call thatdoesn't require voice path to the PBX, the least-cost voice path (calledhairpin voice path) is established directly between the local user andremote office, which bypasses the WAN or IP links between the remoteoffice and the main PBX switch site. If the user tries to use a PBXfeature (i.e., transfer the call) that would require the voice to berouted through the PBX, the invention disables hair-pinning and routesthe voice back to the PBX. The invention manages bandwidth utilizationon the extender WAN or IP link, and if bandwidth is unavailable when theuser tries to use a PBX feature, the call remains hair-pinned and thePBX feature is denied.

[0010] The invention also provides the extension of a PBX trunkinterface to a remote site, allowing a Primary Rate Interface (PRI) atthe remote site to appear as if it is directly connected to the PBX.Users at both the remote site and users directly connected to the PBXmay use this extended trunk for Toll Bypass calls. Users at the remotesite who make use of this local trunk interface can be hair-pinned towith the local trunk, thus conserving the bandwidth which would havenormally been utilized to send the voice call to the PBX and back.

[0011] In one aspect, in a system having a switching device in a firstlocation, and an extending device in a second location such that theextending device extends functionality of the switching device to thesecond location, the invention comprises a method of providing acommunications link between (i) a first phone associated with theextending device and (ii) a second phone local to the second locationand not associated with the extending device. The method includesanalyzing parameters associated with the first phone and the secondphone so as to determine that the first phone and the second phone arelocal to the second location. The method further includes separatingsignaling data associated with the communications link from voicetraffic associated with the communications link. The method furtherincludes directing the signaling data through the switching device viaan extension link between the switching device and the extending device,and directing the voice traffic between the first phone and the secondphone. The novelty of this method is that it works in a heterogeneousenvironment in which a) the switching device doesn't support the voicehairpin concept, b) the extending device interfaces with the switchingdevice—a non-open system on one side and interfaces with a open PSTN onthe other side, and c) calls can be originated from different sourceswith no extra call signal/control information required other than callednumber to make the method work.

[0012] Another embodiment further includes monitoring the communicationslink to determine if one or more features provided by the switchingdevice are required, and directing the voice traffic through theswitching device if the features provided by the switching device arerequired.

[0013] Another embodiment further includes monitoring bandwidthavailable in the communications link, and preventing the voice trafficfrom being directed to the switching device if an amount of availablebandwidth in the communications link is below a predetermined value.

[0014] Another embodiment further includes maintaining the voice trafficbetween the first phone and the second phone if the signaling datathrough the switching device is disrupted.

[0015] Another embodiment further includes managing bandwidth within theextension link between the switching device and the extending device bydividing the extension link bandwidth into distinct partitions.

[0016] Another embodiment further includes dividing each of the distinctpartitions into three distinct pools. One pool includes a free pool,characterized an amount of free bandwidth available in the partition.Another pool includes a used pool, characterized by an amount ofbandwidth actually used in the partition. Another pool includes an idlepool, characterized by an amount of bandwidth allocated but not usedwithin the partition.

[0017] Another embodiment further includes dynamically determining aleast-cost path for the voice traffic, and selectively directing thevoice traffic to the least-cost path.

[0018] Another embodiment further includes providing a trunk interfaceextension from the switching device to the extending device such thateither (i) the first phone, (ii) a third phone associated with theswitching device, or (iii) both the first and third phone use the trunkinterface extension to place a call to the second phone.

[0019] Another embodiment further includes providing a trunk interfaceextension from the switching device to the extending device such thateither (i) the first phone, (ii) a third phone associated with theswitching device, or (iii) both the first phone and the third phone usethe trunk interface extension to receive a call from the second phone.

[0020] In another aspect, the invention comprises a system forhair-pinning voice traffic from a first phone to a second phone within afirst region over a communications link via an extending device in thefirst region. The extending device extends functionality of a switchingdevice in a second region. The system includes a processor for analyzingparameters associated with the first phone and the second phone so as todetermine that the first phone and the second phone are local to thesecond location. In one embodiment, the processor implements a uniquevoice matching pair algorithm that determines whether the first phoneand the second phone are a pair for the intended call. The system alsoincludes a splitter for separating signaling data associated with thecommunications link from voice traffic associated with thecommunications link. The system also includes a multiplexor fordirecting the signaling data through the switching device via anextension link between the switching device and the extending device,and directing the voice traffic between the first phone and the secondphone.

[0021] In another embodiment, the processor monitors the communicationslink to determine if one or more features provided by the switchingdevice are required, and directs the voice traffic through the switchingdevice if the features provided by the switching device are required.

[0022] In another embodiment, the processor monitors bandwidth availablein the communications link, and prevents the voice traffic from beingdirected to the switching device if an amount of available bandwidth inthe communications link is below a predetermined value.

[0023] In another embodiment, the processor maintains the voice trafficbetween the first phone and the second phone if the signaling datathrough the switching device is disrupted.

[0024] In another embodiment, the processor manages bandwidth within theextension link between the switching device and the extending device bydividing the extension link bandwidth into distinct partitions.

[0025] In another embodiment, the processor divides each of the distinctpartitions into three distinct pools. One pool includes a free poolcharacterized an amount of free bandwidth available in the partition.Another pool includes a used pool characterized by an amount ofbandwidth actually used in the partition. Yet another pool includes anidle pool characterized by an amount of bandwidth allocated but not usedwithin the partition.

[0026] In another embodiment, the processor dynamically determines aleast-cost path for the voice traffic, and selectively directs the voicetraffic to the least-cost path.

[0027] Another embodiment further includes a trunk interface extensionfrom the switching device to the extending device wherein either (i) thefirst phone, (ii) a third phone associated with the switching device, or(iii) both the first and third phone uses the trunk interface extensionto place a call to the second phone.

[0028] Another embodiment further includes a trunk interface extensionfrom the switching device to the extending device wherein either (i) thefirst phone, (ii) a third phone associated with the switching device, or(iii) both the first phone and the third phone uses the trunk interfaceextension to receive a call from the second phone.

[0029] In another aspect, the invention comprises a system fortransmitting voice traffic from a first phone within a first region to asecond phone within the first region via a communications link. Thesystem includes a switching device resident in a second region remotefrom the first region, wherein the switching device provides one or morecommunications features related to telephone communications. The systemalso includes an extending device resident in the first region, local toand electrically coupled to the first phone, wherein the extendingdevice communicates with the switching device via an extension link andextends functionality of the switching device such that thecommunications features are available in the first region. The extendingdevice (i) analyzes parameters associated with the first phone and thesecond phone so as to determine that the first phone and the secondphone are local to the second location, and they are a pair for theintended call, (ii) separates signaling data associated with thecommunications link from voice traffic associated with thecommunications link, and (iii) directs the signaling data through theswitching device via an extension link between the switching device andthe extending device, and directs the voice traffic between the firstphone and the second phone.

[0030] In another embodiment, the switching device includes a PBXswitching system.

[0031] In another embodiment, the extension link includes one or morecommunications channels through the public switch telephone network.

[0032] In another embodiment, the one or more communications featuresincludes PBX functions and features.

[0033] In another embodiment, wherein the PBX functions and featuresinclude call forwarding, call waiting, voicemail, call transfer,conferencing or combinations thereof.

[0034] In another embodiment, the system uses a flow control mechanismsuch as Adaptive Frame Length Control (AFLC) to solve mismatched packettransmit and receive rate problem when a packetizing/unpacketizingdevice (e.g., QMC—a Motorola QUICC multichannel controller) is deployedto packetize/unpacketize raw PCM voice from/to T1/PRI/E1 interface. Thenovelty of the AFLC is that it works in a deployment in which twopacketizing/unpacketizing devices to be sync up are separated by apacketized network (e.g., IP); there is no physical sync controlmechanism available between the two devices; and c) two devices aregeneral-purpose IO control devices (e.g., not ASIC/FPGA/DSP which arespecifically engineered for packetized voice applications). Theuniqueness of the mechanism is also with its low-overhead, simplicity,and easy implementation in software.

BRIEF DESCRIPTION OF DRAWINGS

[0035] The foregoing and other objects of this invention, the variousfeatures thereof, as well as the invention itself, may be more fullyunderstood from the following description, when read together with theaccompanying drawings in which:

[0036]FIG. 1 shows a prior art system with a PBX switch in a centraloffice in city X remotely connected to an extender in a different cityY;

[0037]FIG. 2 shows a block diagram view of a system for hair-pinningvoice traffic from a first phone to a second phone that are bothsituated within a first region;

[0038]FIG. 3 shows a system similar to the one shown in FIG. 2, exceptwith more specific components;

[0039]FIG. 4 shows the system of FIG. 3 without hair-pinning, with voicetraffic shown explicitly;

[0040]FIG. 5 shows the system of FIG. 3 with hair-pinning, with voicetraffic shown explicitly; and,

[0041]FIG. 6 shows a logical flow of the algorithm for finding a correct1-1 mapping out of N local trunk calls and N switch calls.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042]FIG. 2 shows a block diagram view of one preferred embodiment of asystem 100 for hair-pinning voice traffic from a first phone 102 to asecond phone 104 that are both situated within a first region 106. Thesystem includes a switching device 108 located in a second region 110,and an extending device 112 (also referred to herein as “extender”) thatextends the facilities and features of the switching device 108 into thesecond region 106. The extending device 112 communicates with theswitching device 108 via a gateway 114 located at or near the switchingdevice 108, through an extending link 116 that exists, at leastpartially, within the PSTN. In one embodiment, the switching device 108includes a PBX switch, although other embodiments may use other types ofswitching devices known in the art. The hair-pinning occurs over acommunications link 118 that passes through the extending device 112.The system includes a processor 120 that analyzes parameters associatedwith the first phone 102 and the second phone 104 to determine therelative locations of the first and second phones. The processor 120then allows hair-pinning to occur only if the first and second phonesare local to the first region 110 and they are a pair for the intendedcall based on the voice matching pair algorithm described herein. Notethat the “first region” may be any predetermined physical space. Forexample, the first region may include a city, a neighborhood, abuilding, a country, or any other region that can be spatially delimitedin some way. In the embodiment shown in FIG. 2, the processor 120resides in the extender device 112, although in other embodiments theprocessor may reside in a separate, independent location, or in someother location that allows access to the parameters necessary fordetermining the locations of the first and second phones. Thecommunications link 118 that connects the first phone 102 to the secondphone 104 consists of bi-directional voice traffic generated by theusers of the two phones, as well as lower rate signaling data thataccompanies the voice traffic and provides control and other functions.The system also includes a splitter 122 and a multiplexor 124. Thesplitter 122 separates signaling data 126 associated with thecommunications link 118 from voice traffic 128 associated with thecommunications link 118 to generate two separate streams of information.The multiplexor 124 receives the separated streams of information anddirects the signaling data 126 through the switching device 108 via theextension link 116 between the switching device 108 and the extendingdevice 112. The multiplexor 124 also directs the voice traffic 128 topass directly between the first phone 102 and the second phone 104. Forsimplicity in FIG. 2, only the information passing from the first phone102 to the second phone 104 is shown. It is understood that thecommunications between the first phone 102 and the second phone 104 isbi-directional, so that the splitter 122 and the multiplexor 124 alsoperform similar functions for the data passing from the second phone 104to the first phone 102.

[0043] The term “hair-pinning” refers to the voice traffic beingdiverted through the extender 112 without having to pass through theswitching device 108 as with the prior art system shown in FIG. 1. Inother embodiments, hairpinning as described herein may also occur via aKTS, a PBX or a gateway device. While hair-pinning is in effect, theusers of the first phone 102 and the second phone 104 cannot takeadvantage of the functions and features of the switching device. Inorder to allow dynamic access to those functions and features, theprocessor 120 monitors the communications link 118 between the firstphone 102 and the second phone 104 to determine if the functions andfeatures provided by the switching device are required. If so, theprocessor configures the extender 112 to direct the voice trafficthrough the switching device via the extension link 116, therebyeliminating the hair-pinning, so that the voice traffic through theswitching device 108 via the extension link 116. The processor 120monitors the bandwidth available on the extension link 116 and onlyallows voice traffic to be transmitted on the extension link 116 ifsufficient bandwidth is available.

[0044] During a normal hair-pinning operation, voice traffic flowsdirectly between the two terminating phones, while the associatedsignaling data is routed through the switching device 108 via theextension link 116. If the signaling data is disrupted at any pointalong its path through the switching device 108, the processor 120maintains the voice traffic between the two terminating phones. In someembodiments, the processor 120 provides notification of the disruptionto the users of the two terminating phones, and further attempts tore-establish the signaling data path through the switching device 108.In other embodiments, the processor 120 may allow the voice trafficcontinue without signaling data until the voice traffic ends.

[0045] To support fast switching between ordinary (i.e., non-hairpinned)voice routing and hairpinned voice routing, the processor 120 implementsan effective bandwidth management scheme which divides traffic on theextension link 116 into two or more partitions, and groups the overallbandwidth in each partition into three distinct pools. The “free pool”tracks the amount of free bandwidth available in a particular partition.The “used pool” tracks the amount of bandwidth actually used in aparticular partition. The “idle pool” tracks the amount of bandwidthallocated but not used in a partition due to the hair-pinning. This is acommon bandwidth management scheme that applies to all types of widearea network (WAN) (e.g., T1, FT1, PRI, V.35/RS530/RS232 serial I/F) andIP links.

[0046] The hairpin path for the voice traffic is also referred to hereinas the “least cost” path. Prior art PBX extenders required users to makeexternal calls through the PBX switch on a trunk line local to the PBXswitch. If the remote location is in a different calling area then thePBX switch, the user may incur toll charges to call phone number thatwould normally be local to the calling area. Hair-pinning avoids thisresult, thereby creating a least cost path. The least-cost voice path isdynamically changed to respond to features an extended user (i.e., oneof the users connected through the extender 112) accesses. If a featurethe extended user is accessing does not require a voice path back to thePBX switch, the voice path can be hair-pinned directly at the remoteoffice site. All remote phones/PRI (Primary Rate Interface, e.g., T1)channels at the extended site can be used to initiate voice callswithout using any voice bandwidth on the connection between the extendedsite (i.e., first region) and the main office (i.e., PBX site—secondregion). The voice quality on hair-pinned calls is significantlyimproved because the voice is directly connected, as compared to beingpacketized, compressed, echo cancelled and delayed in the extension link116 to the PBX switch 108 and back.

[0047] The embodiment of FIG. 2 also provides a “Toll Bypass” feature byextending the trunk interface from the PBX switch 108 all the way to theremote site and interfacing, via the extending device 112, with the PRIthat is local to the extending device 112. The PBX trunk interface isextended over extension link 116. Both remote phones (i.e., phonesconnected to the extender 112) and phones directly connected the PBXswitch 108 have access to the Toll Bypass feature. Thus, a phoneconnected to the PBX switch 108 in region 2 can place a call to a PRIlocal to region 1 over the extension link 116, without incurring thelong distance charges that would normally accrue if the call was madevia the trunk interface in region 2.

[0048]FIG. 3 shows a system similar to the system of FIG. 2, except withthe extender device shown as an MCK Extender 7000, and the gateway isshown as an MCK Gateway 2. In FIG. 3, an outside caller at the firstphone 202 calls the DID associated with the second phone 204 on anExtended Digital Port of the Extender 7000. The sequence of events areas follows:

[0049] 1. Outside caller in city Y calls the DID on the 7000 local PRIassociated with the Extended Digital Port.

[0050] 2. The 7000 local central office (CO) PRI signals an incomingcall.

[0051] 3. Extender 7000 212 routes the call via MCK Extender Link 216 tothe Gateway 2 214, reserving bandwidth for this call.

[0052] 4. Gateway 2 routes the call via Gateway 2 T1/PRI (TrunkInterface) to the PBX PRI/T1 trunk interface.

[0053] 5. The PBX 208 detects the incoming call and determines it is forthe Digital port associated with the second phone 204.

[0054] 6. The PBX 208 routes the call to the digital port connected tothe Gateway 2 214.

[0055] 7. The Gateway 2 214 routes the call to the Extender 7000 212 viathe MCK Extender Link 216, reserving bandwidth for this call.

[0056] 8. The Extender 7000 routes the call to the Extender 7000 phone.

[0057]FIG. 4 shows the system of FIG. 3 with the voice path 250illustrated explicitly as:

[0058] Remote PRI→Extender 7000→Gateway 2→PBX→Gateway 2→Extender7000→Extender 7000 Digital Phone.

[0059] The system detects the situation of FIG. 4 and performshair-pinning, connecting the Remote PRI to the Extender 7000 digitalphone. The voice connection that travels to the PBX 208 and back isremoved from the extension link 216, and the bandwidth reserved for thisconnection is freed. The phone signaling still goes to the PBX 208 andback, just the voice connection is hair-pinned at the Extender 7000 212.This provides the effect of having a phone call through the PBX. FIG. 5shows the system of FIG. 3 with the hairpinned voice path 252 shownexplicitly.

[0060] The paths for a call from the first phone 202 to the second phone204 is the same as for a call from the second phone 204 to the firstphone 202.

[0061] In one embodiment, the processor 120 implements a unique voicematching pair algorithm that determines whether the first phone and thesecond phone are a pair for the intended call. Refer to FIG. 6 forgeneral description of the voice matching pair algorithm. The voicematching algorithm is universal, which works on PBX protocols. For anexample of a typical problem for which the algorithm may be used tosolve, suppose there are N inbound/outbound calls from/to the PSTNdetected on a local trunk interface at the extending device, and thereare another M inbound/outbound calls from/to the switch side detected onan extender interface. The voice matching pair algorithm described inFIG. 6 provides the correct 1-1 mapping out of N-M relationships so thatthe system can directly hairpin the voice path for this 1-1 pair at theextending device.

[0062] Another aspect of the invention is the Adaptive Frame LengthControl (AFLC) mechanism used in packetizing/unpacketizing raw PCM voicestream process for improving audio quality. Basically, a QMC device(e.g., a Motorola QUICC multichannel controller) or other similarpacketizing device is used to packetize raw PCM voice stream fromT1/PRI/E1 interface, and then the host transmits the raw PCM voicepackets to the other end of packetized network (e.g., IP). Another QMCdevice or other similar unpacketizing device on the other end of thenetwork unpacketizes the packets into T1/PRI/E1 bit stream. This processis taken in both directions. In order to get good quality of voice viathe packetizing/unpacketizing process, packet arrival rate from apacketizing device on one end has to be in synchronization with packettransmit rate to a unpacketizing device on the other end. If packetarrival rate from one end is faster than packet transmit rate on theother end, then there will be transmit overrun packet loss which willresult into poor audio. If packet arrival rate from one end is slowerthan packet transmit rate on the other end, then there will be transmitunder-run problem which will result in poor audio too. Unfortunately,normal voice packetizing scheme used for DSP will not work in this caseand will have the mis-matched QMC packet arrival rate and packettransmit rate problem. The existing voice packetizing scheme will eitherrequire all packets to be transmitted with the same frame length orwithout frame boundary in transmitting. The fixed transmit frame lengthwill result in packet loss due to transmit overrun. The reason why thefixed frame will have transmit overrun is that QMC or similar devicewill not be guaranteed to transmit frames of fixed length in a constantrate that is in sync with packet arrival rate due to T1/E1 frame syncdelay in transmitting. Transmitting all packets without frame boundarywill cause transmit packet under-run problem because the packet transmitrate will be faster than packet arrival rate, specifically with delayintroduced in packetized network (e.g., IP).

[0063] The AFLC flow control mechanism overcomes the mismatched packetarrival and transmit rate problem by dynamically adjusting transmitframe boundary based on certain parameters such as the current transmitqueue length, maximum transmit queue length, lower water-mark forturning on constant bit transmitting (i.e., transmit queued packets as acontinuous bit stream without setting frame end flag), upper water-markfor turning off constant bit transmitting (i.e., end the currentcontinuous bit stream with a frame end flag). By analyzing transmitqueue length and other configurable parameters dynamically, the AFLC canpredict whether the packet transmit rate is out of sync with packetarrival rate and the transmit rate shifts out in which direction (i.e.,faster or slower than arrival rate). If it becomes faster, the AFLC willadjust frame boundary accordingly to slow down packet transmit rate to async point. If it becomes slower, the AFLC will adjust frame boundaryaccordingly to speed up packet transmit rate to a sync point. The AFLCwill greatly improve audio quality because it virtually eliminatespacket overrun and under-run problems. The AFLC can be used to improvenot only audio quality but also other real-time applications such asvideo. The AFLC may be implemented in software running on a computersystem, or it may be implemented in hardware (i.e., an applicationspecific integrated circuit), or it may be implemented in a combinationof software and hardware, such as a microcontroller system running onfirmware, or any other similar technique known in the art ofimplementing such an algorithm.

[0064] The invention may be embodied in other specific forms withoutdeparting from the spirit or essential characteristics thereof. Thepresent embodiments are therefore to be considered in respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofthe equivalency of the claims are therefore intended to be embracedtherein.

What is claimed is:
 1. In a system having a switching device in a firstlocation, and an extending device in a second location, wherein theextending device extends functionality of the switching device to thesecond location, a method of providing a communications link between (i)a first phone associated with the extending device and (ii) a secondphone local to the second location and not associated with the extendingdevice, the method comprising: analyzing parameters associated with thefirst phone and the second phone so as to determine that the first phoneand the second phone are local to the second location and are a pair forthe intended call; separating signaling data associated with thecommunications link from voice traffic associated with thecommunications link; directing the signaling data through the switchingdevice via an extension link between the switching device and theextending device, and directing the voice traffic between the firstphone and the second phone.
 2. A system according to claim 1, furtherincluding analyzing the parameters associated with the first phone andthe second phone with a voice matching pair algorithm, so as todetermine that the first phone and the second phone are a pair for theintended call.
 3. A method according to claim 1, further includingmonitoring the communications link to determine if one or more featuresprovided by the switching device are required, and directing the voicetraffic through the switching device if the features provided by theswitching device are required.
 4. A method according to claim 3, furtherincluding monitoring bandwidth available in the communications link, andpreventing the voice traffic from being directed to the switching deviceif an amount of available bandwidth in the communications link is belowa predetermined value.
 5. A method according to claim 1, furtherincluding maintaining the voice traffic between the first phone and thesecond phone if the signaling data through the switching device isdisrupted.
 6. A method according to claim 1, further including managingbandwidth within the extension link between the switching device and theextending device by dividing the extension link bandwidth into distinctpartitions.
 7. A method according to claim 6, further including dividingeach of the distinct partitions into three distinct pools, including (i)a free pool characterized an amount of free bandwidth available in thepartition, (ii) a used pool characterized by an amount of bandwidthactually used in the partition, and (iii) an idle pool characterized byan amount of bandwidth allocated but not used within the partition.
 8. Amethod according to claim 1, further including dynamically determining aleast-cost path for the voice traffic, and selectively directing thevoice traffic to the least-cost path.
 9. A method according to claim 1,further including providing a trunk interface extension from theswitching device to the extending device such that either (i) the firstphone, (ii) a third phone associated with the switching device, or (iii)both the first and third phone use the trunk interface extension toplace a call to the second phone.
 10. A method according to claim 1,further including providing a trunk interface extension from theswitching device to the extending device such that either (i) the firstphone, (ii) a third phone associated with the switching device, or (iii)both the first phone and the third phone use the trunk interfaceextension to receive a call from the second phone.
 11. A system forhair-pinning voice traffic from a first phone to a second phone within afirst region over a communications link via an extending device in thefirst region, wherein the extending device extends functionality of aswitching device in a second region, comprising a processor foranalyzing parameters associated with the first phone and the secondphone so as to determine that the first phone and the second phone arelocal to the second location; a splitter for separating signaling dataassociated with the communications link from voice traffic associatedwith the communications link; a multiplexor for directing the signalingdata through the switching device via an extension link between theswitching device and the extending device, and directing the voicetraffic between the first phone and the second phone.
 12. A systemaccording to claim 11, wherein the processor monitors the communicationslink to determine if one or more features provided by the switchingdevice are required, and directs the voice traffic through the switchingdevice if the features provided by the switching device are required.13. A system according to claim 12, wherein the processor monitorsbandwidth available in the communications link, and prevents the voicetraffic from being directed to the switching device if an amount ofavailable bandwidth in the communications link is below a predeterminedvalue.
 14. A system according to claim 11, wherein the processormaintains the voice traffic between the first phone and the second phoneif the signaling data through the switching device is disrupted.
 15. Asystem according to claim 11, wherein the processor manages bandwidthwithin the extension link between the switching device and the extendingdevice by dividing the extension link bandwidth into distinctpartitions.
 16. A system according to claim 15, wherein the processordivides each of the distinct partitions into three distinct pools,including (i) a free pool characterized an amount of free bandwidthavailable in the partition, (ii) a used pool characterized by an amountof bandwidth actually used in the partition, and (iii) an idle poolcharacterized by an amount of bandwidth allocated but not used withinthe partition.
 17. A system according to claim 11, wherein the processordynamically determines a least-cost path for the voice traffic, andselectively directs the voice traffic to the least-cost path.
 18. Asystem according to claim 11, further including a trunk interfaceextension from the switching device to the extending device whereineither (i) the first phone, (ii) a third phone associated with theswitching device, or (iii) both the first and third phone uses the trunkinterface extension to place a call to the second phone.
 19. A systemaccording to claim 11, further including a trunk interface extensionfrom the switching device to the extending device wherein either (i) thefirst phone, (ii) a third phone associated with the switching device, or(iii) both the first phone and the third phone uses the trunk interfaceextension to receive a call from the second phone.
 20. A systemaccording to claim 11, further including means for mitigating mismatchedpacket transmit and receive rates associated with a packet flow.
 21. Asystem according to claim 20, wherein the means for mitigatingmismatched packet transmit and receive rates includes a flow controlmechanism.
 22. A system according to claim 21, wherein the flow controlmechanism (i) gathers one or more parameters associated with the packetflow, and (ii) adjusts a transmit frame boundary so as to dynamicallyvary the transmit rate to substantially match the arrival rate.
 23. Asystem according to claim 22, wherein the one or more parametersassociated with the packet flow is selected from the group consisting of(i) current transmit queue length, (ii) maximum transmit queue length,(iii) lower water-mark for turning on constant bit transmitting, (iv)upper water-mark for turning off constant bit transmitting, andcombinations thereof.
 24. A system for transmitting voice traffic from afirst phone within a first region to a second phone within the firstregion via a communications link, comprising a switching device residentin a second region remote from the first region, wherein the switchingdevice provides one or more communications features related to telephonecommunications; an extending device resident in the first region, localto and electrically coupled to the first phone, wherein the extendingdevice communicates with the switching device via an extension link andextends functionality of the switching device such that thecommunications features are available in the first region; wherein theextending device (i) analyzes parameters associated with the first phoneand the second phone so as to determine that the first phone and thesecond phone are local to the second location, (ii) separates signalingdata associated with the communications link from voice trafficassociated with the communications link, and (iii) directs the signalingdata through the switching device via an extension link between theswitching device and the extending device, and directs the voice trafficbetween the first phone and the second phone.
 25. A system according toclaim 24, wherein the switching device includes a PBX switching system.26. A system according to claim 24, wherein the extension link includesone or more communications channels through the public switch telephonenetwork.
 27. A system according to claim 24, wherein the one or morecommunications features includes PBX functions and features.
 28. Asystem according to claim 27, wherein the PBX functions and featuresinclude call forwarding, call waiting, voicemail, call transfer,conferencing or combinations thereof.
 29. A system flow controlmechanism for mitigating mismatched packet transmit and receive ratesassociated with a packet flow at a PRI, comprising: means for gatheringone or more parameters associated with the packet flow, and means foradjusting a transmit frame boundary so as to dynamically vary thetransmit rate to substantially match the arrival rate.
 30. A systemaccording to claim 29, wherein the one or more parameters associatedwith the packet flow is selected from the group consisting of (i)current transmit queue length, (ii) maximum transmit queue length, (iii)lower water-mark for turning on constant bit transmitting, (iv) upperwater-mark for turning off constant bit transmitting, and combinationsthereof.
 31. A method of mitigating mismatched packet transmit andreceive rates associated with a packet flow at a PRI, comprising:gathering one or more parameters associated with the packet flow, and,adjusting a transmit frame boundary so as to dynamically vary thetransmit rate to substantially match the arrival rate.